| the hfq-like protein nrfa of the phototrophic purple bacterium rhodobacter capsulatus controls nitrogen fixation via regulation of nifa and anfa expression. | the rhodobacter capsulatus nrfa gene product exhibits extensive similarity to the nif (nitrogen fixation) regulatory factor nrfa of azorhizobium caulinodans and the nucleoid-associated protein hfq of escherichia coli. mutational analysis revealed that, in contrast to the situation in a. caulinodans, nrfa is not essential for diazotrophic growth of r. capsulatus, but it is required for maximal growth rates with n(2) as sole nitrogen source via either molybdenum nitrogenase or the alternative nitr ... | 2002 | 12399038 |
| a new species of devosia that forms a unique nitrogen-fixing root-nodule symbiosis with the aquatic legume neptunia natans (l.f.) druce. | rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. however, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in african soils is nodulated by allorhizobium undicola. this legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. here, we analyzed ... | 2002 | 12406707 |
| prediction and overview of the rpon-regulon in closely related species of the rhizobiales. | in the rhizobia, a group of symbiotic gram-negative soil bacteria, rpon (sigma54, sigman, ntra) is best known as the sigma factor enabling transcription of the nitrogen fixation genes. recent reports, however, demonstrate the involvement of rpon in other symbiotic functions, although no large-scale effort has yet been undertaken to unravel the rpon-regulon in rhizobia. we screened two complete rhizobial genomes (mesorhizobium loti, sinorhizobium meliloti) and four symbiotic regions (rhizobium et ... | 2002 | 12537565 |
| a rhizobium leguminosarum acpxl mutant produces lipopolysaccharide lacking 27-hydroxyoctacosanoic acid. | the structure of the lipid a from rhizobium etli and rhizobium leguminosarum lipopolysaccharides (lpss) lacks phosphate and contains a galacturonosyl residue at its 4' position, an acylated 2-aminogluconate in place of the proximal glucosamine, and a very long chain omega-1 hydroxy fatty acid, 27-hydroxyoctacosanoic acid (27ohc28:0). the 27ohc28:0 moiety is common in lipid a's among members of the rhizobiaceae and also among a number of the facultative intracellular pathogens that form chronic i ... | 2003 | 12618448 |
| influence of cell wall degrading enzymes on colonization of n2 fixing bacterium, azorhizobium caulinodans in rice. | in rice, nodule like structures were formed by inoculation of a. caulinodans combined with growth regulators and enzymes. among the treatments, combination of cell wall degrading enzyme mixture and naa with a. caulinodans induced more number of paranodules in rice. total nitrogen content also increased in treated plants compared to uninoculated control. | 2002 | 12635715 |
| inactivation of the nod box distal half-site allows tetrameric nodd to activate noda transcription in an inducer-independent manner. | in rhizobium leguminosarum, nodd can activate noda transcription in response to inducer flavonoids. here, we show that the inducible noda promoter contains an intrinsic part through which nodd can activate noda transcription in an inducer-independent manner. evidence was provided that nodd binds to target dna through anchoring the two half-sites of the nod box as a tetramer. an imperfect inverted repeat at-n10-gat was found in each half-site and is critical for nodd binding. mutation of the inve ... | 2003 | 12799442 |
| sm-like proteins in eubacteria: the crystal structure of the hfq protein from escherichia coli. | the hfq protein was discovered in escherichia coli in the early seventies as a host factor for the qbeta phage rna replication. during the last decade, it was shown to be involved in many rna processing events and remote sequence homology indicated a link to spliceosomal sm proteins. we report the crystal structure of the e.coli hfq protein showing that its monomer displays a characteristic sm-fold and forms a homo-hexamer, in agreement with former biochemical data. overall, the structure of the ... | 2003 | 12853626 |
| spatial distribution of rhodopseudomonas palustris ecotypes on a local scale. | the number, spatial distribution, and significance of genetically distinguishable ecotypes of prokaryotes in the environment are poorly understood. oda et al. (y. oda, b. star, l. a. huisman, j. c. gottschal, and l. j. forney, appl. environ. microbiol. 69:xxx-xxx, 2003) have shown that rhodopseudomonas palustris ecotypes were lognormally distributed along a 10-m transect and that multiple strains of the species could coexist in 0.5-g sediment samples. to extend these observations, we investigate ... | 2003 | 12957901 |
| phenotypic changes resulting from distinct point mutations in the azospirillum brasilense glna gene, encoding glutamine synthetase. | sequencing the glna genes of two chemically induced azospirillum brasilense glutamine synthetase mutants revealed an arg-->cys mutation, corresponding to the glutamate binding site, in one mutant and an asp-->asn mutation, corresponding to the ammonium binding site, in the second mutant. the phenotypic changes in these mutants are discussed in relation to their genotypes. | 2003 | 12957965 |
| isolation and characterization of periplasmic cyclic beta-glucans of azorhizobium caulinodans. | oligoglucose molecules isolated from azorhizobium caulinodans were characterized by compositional analysis, smith degradation, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and (1)h and (13)c nuclear magnetic resonance analysis. a. caulinodans produced nonbranched and unsubstituted cyclic glucans composed solely of glucose, with the degree of polymerization ranging from 10 to 13. a major fraction of the periplasmic glucans contains 11 glucose residues within rings ... | 2003 | 14592718 |
| microaerophilic cooperation of reductive and oxidative pathways allows maximal photosynthetic membrane biosynthesis in rhodospirillum rubrum. | the purple nonsulfur bacterium rhodospirillum rubrum has been employed to study physiological adaptation to limiting oxygen tensions (microaerophilic conditions). r. rubrum produces maximal levels of photosynthetic membranes when grown with both succinate and fructose as carbon sources under microaerophilic conditions in comparison to the level (only about 20% of the maximum) seen in the absence of fructose. employing a unique partial o(2) pressure (po(2)) control strategy to reliably adjust the ... | 2003 | 14602616 |
| legume symbiotic nitrogen fixation by beta-proteobacteria is widespread in nature. | following the initial discovery of two legume-nodulating burkholderia strains (l. moulin, a. munive, b. dreyfus, and c. boivin-masson, nature 411:948-950, 2001), we identified as nitrogen-fixing legume symbionts at least 50 different strains of burkholderia caribensis and ralstonia taiwanensis, all belonging to the beta-subclass of proteobacteria, thus extending the phylogenetic diversity of the rhizobia. r. taiwanensis was found to represent 93% of the mimosa isolates in taiwan, indicating that ... | 2003 | 14645288 |
| azorhizobium caulinodans electron-transferring flavoprotein n electrochemically couples pyruvate dehydrogenase complex activity to n2 fixation. | azorhizobium caulinodans thermolabile point mutants unable to fix n2 at 42 degrees c were isolated and mapped to three, unlinked loci; from complementation tests, several mutants were assigned to the fixabcx locus. of these, two independent fixb mutants carried missense substitutions in the product electron-transferring flavoprotein n (etfn) alpha-subunit. both thermolabile missense variants y238h and d229g mapped to the etfnalpha interdomain linker. unlinked thermostable suppressors of these tw ... | 2004 | 14702404 |
| a rhizobium leguminosarum lipopolysaccharide lipid-a mutant induces nitrogen-fixing nodules with delayed and defective bacteroid formation. | lipopolysaccharides from pea-nodulating strain rhizobium leguminosarum by. viciae 3841, as all other members of the family rhizobiaceae with the possible exception of azorhizobium caulinodans, contains a very long chain fatty acid; 27-hydroxyoctacosanoic acid (27ohc28:0) in its lipid a region. the exact function and importance of this residue, however, is not known. in this work, a previously constructed mutant, rhizobium leguminosarum by. viciae 22, deficient in the fatty acid residue, was anal ... | 2004 | 15000395 |
| regulatory role of rhizobium etli cnpaf512 fnrn during symbiosis. | the rhizobium etli cnpaf512 fnrn gene was identified in the fixabcx rpon(2) region. the corresponding protein contains the hallmark residues characteristic of proteins belonging to the class ib group of fnr-related proteins. the expression of r. etli fnrn is highly induced under free-living microaerobic conditions and during symbiosis. this microaerobic and symbiotic induction of fnrn is not controlled by the sigma factor rpon and the symbiotic regulator nifa or fixlj, but it is due to positive ... | 2004 | 15006745 |
| the fixabcx genes in rhodospirillum rubrum encode a putative membrane complex participating in electron transfer to nitrogenase. | in our efforts to identify the components participating in electron transport to nitrogenase in rhodospirillum rubrum, we used mini-tn5 mutagenesis followed by metronidazole selection. one of the mutants isolated, snt-1, exhibited a decreased growth rate and about 25% of the in vivo nitrogenase activity compared to the wild-type values. the in vitro nitrogenase activity was essentially wild type, indicating that the mutation affects electron transport to nitrogenase. sequencing showed that the t ... | 2004 | 15028689 |
| structural characterization of extracellular polysaccharides of azorhizobium caulinodans and importance for nodule initiation on sesbania rostrata. | during lateral root base nodulation, the microsymbiont azorhizobium caulinodans enters its host plant, sesbania rostrata, via the formation of outer cortical infection pockets, a process that is characterized by a massive production of h(2)o(2). infection threads guide bacteria from infection pockets towards nodule primordia. previously, two mutants were constructed that produce lipopolysaccharides (lpss) similar to one another but different from the wild-type lps, and that are affected in extra ... | 2004 | 15066035 |
| switch from intracellular to intercellular invasion during water stress-tolerant legume nodulation. | rhizobia colonize their legume hosts by different modes of entry while initiating symbiotic nitrogen fixation. most legumes are invaded via growing root hairs by the root hair-curl mechanism, which involves epidermal cell responses. however, invasion of a number of tropical legumes happens through fissures at lateral root bases by cortical, intercellular crack entry. in the semiaquatic sesbania rostrata, the bacteria entered via root hair curls under nonflooding conditions. upon flooding, root h ... | 2004 | 15079070 |
| a gfp reporter plasmid to visualize azorhizobium caulinodans during nodulation of sesbania rostrata. | compared with other labeling techniques, the use of the green fluorescent protein (gfp) is advantageous to visualize bacteria because observations can be performed in real time. this feature is particularly interesting to study invasion events of rhizobia during nodule development on their legume host plant. to investigate the symbiotic interaction between azorhizobium caulinodans ors571 and sesbania rostrata, we constructed two plasmids, pmp220-hem-gfp5 and pbbr5-hem-gfp5-s65t, that carry a mod ... | 2004 | 15109825 |
| molecular and functional characterization of the azorhizobium caulinodans ors571 hydrogenase gene cluster. | in this work, we report the cloning and sequencing of the azorhizobium caulinodans ors571 hydrogenase gene cluster. sequence analysis revealed the presence of 20 open reading frames huptuvhypfhupslcdfghjk hypabhuprhypcdehupe. the physical and genetic organization of a. caulinodans ors571 hydrogenase system suggests a close relatedness to that of rhodobacter capsulatus. in contrast to the latter species, a gene homologous to rhizobium leguminosarum hupe was identified downstream of the hyp operon ... | 2004 | 15321689 |
| symbiotic autoregulation of nifa expression in rhizobium leguminosarum bv. viciae. | nifa is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. in rhizobium leguminosarum bv. viciae upm791, the nifa gene is part of a gene cluster (orf71 orf79 fixw orf5 fixabcx nifab) separated by 896 bp from an upstream and divergent truncated duplication of nifh (deltanifh). symbiotic expression analysis of genomic nifa::lacz fusions revealed that in strain upm791 nifa is expressed mainly from a sigma54-dependent promoter (p(nifa1)) located upstream of or ... | 2004 | 15375140 |
| transcriptional analysis of biofilm formation processes in the anaerobic, hyperthermophilic bacterium thermotoga maritima. | thermotoga maritima, a fermentative, anaerobic, hyperthermophilic bacterium, was found to attach to bioreactor glass walls, nylon mesh, and polycarbonate filters during chemostat cultivation on maltose-based media at 80 degrees c. a whole-genome cdna microarray was used to examine differential expression patterns between biofilm and planktonic populations. mixed-model statistical analysis revealed differential expression (twofold or more) of 114 open reading frames in sessile cells (6% of the ge ... | 2004 | 15466556 |
| engineering of chimeric class ii polyhydroxyalkanoate synthases. | pha synthase is a key enzyme involved in the biosynthesis of polyhydroxyalkanoates (phas). using a combinatorial genetic strategy to create unique chimeric class ii pha synthases, we have obtained a number of novel chimeras which display improved catalytic properties. to engineer the chimeric pha synthases, we constructed a synthetic phac gene from pseudomonas oleovorans (phac1po) that was devoid of an internal 540-bp fragment. randomly amplified pcr products (created with primers based on conse ... | 2004 | 15528546 |
| diversity in a promiscuous group of rhizobia from three sesbania spp. colonizing ecologically distinct habitats of the semi-arid delhi region. | sesbania-rhizobia associations have immense significance in soil amelioration programs for diverse habitats. diversity in symbiotic properties, lps profiles, sym plasmid and rhizobiophage sensitivity of 28 root- and stem-nodulating bacterial isolates of three sesbania species (s. sesban, s. aegyptica and s. rostrata) inhabiting six ecologically distinct sites of semi-arid delhi region was analyzed. the isolates were highly promiscuous among the symbiotic partners (sesbania spp.). the root nodule ... | 2005 | 15636748 |
| lipopolysaccharides as a communication signal for progression of legume endosymbiosis. | establishment of a successful symbiosis between rhizobia and legumes results from an elaborate molecular dialogue between both partners. bacterial nodulation (nod) factors are indispensable for initiating plant responses, whereas bacterial surface polysaccharides are important for infection progression and nodule development. the mutant ors571-oac2 of azorhizobium caulinodans, affected in its surface polysaccharides, provokes a defective interaction with its host sesbania rostrata. ors571-oac2 i ... | 2005 | 15699329 |
| invasion of lotus japonicus root hairless 1 by mesorhizobium loti involves the nodulation factor-dependent induction of root hairs. | in many legumes, including lotus japonicus and medicago truncatula, susceptible root hairs are the primary sites for the initial signal perception and physical contact between the host plant and the compatible nitrogen-fixing bacteria that leads to the initiation of root invasion and nodule organogenesis. however, diverse mechanisms of nodulation have been described in a variety of legume species that do not rely on root hairs. to clarify the significance of root hairs during the l. japonicus-me ... | 2005 | 15778455 |
| methylocella species are facultatively methanotrophic. | all aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. here we demonstrate that members of the recently discovered genus methylocella are an exception to this. these bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. to conclusively verify facultative growth, acetate and methane were used as model ... | 2005 | 15968078 |
| e1 enzyme of the pyruvate dehydrogenase complex in corynebacterium glutamicum: molecular analysis of the gene and phylogenetic aspects. | the e1p enzyme is an essential part of the pyruvate dehydrogenase complex (pdhc) and catalyzes the oxidative decarboxylation of pyruvate with concomitant acetylation of the e2p enzyme within the complex. we analyzed the corynebacterium glutamicum acee gene, encoding the e1p enzyme, and constructed and characterized an e1p-deficient mutant. sequence analysis of the c. glutamicum acee gene and adjacent regions revealed that acee is not flanked by genes encoding other enzymes of the pdhc. transcrip ... | 2005 | 16109942 |
| two-component signal transduction pathways regulating growth and cell cycle progression in a bacterium: a system-level analysis. | two-component signal transduction systems, comprised of histidine kinases and their response regulator substrates, are the predominant means by which bacteria sense and respond to extracellular signals. these systems allow cells to adapt to prevailing conditions by modifying cellular physiology, including initiating programs of gene expression, catalyzing reactions, or modifying protein-protein interactions. these signaling pathways have also been demonstrated to play a role in coordinating bact ... | 2005 | 16176121 |
| gibberellins are involved in nodulation of sesbania rostrata. | upon submergence, azorhizobium caulinodans infects the semiaquatic legume sesbania rostrata via the intercellular crack entry process, resulting in lateral root-based nodules. a gene encoding a gibberellin (ga) 20-oxidase, srga20ox1, involved in ga biosynthesis, was transiently up-regulated during lateral root base nodulation. two srga20ox1 expression patterns were identified, one related to intercellular infection and a second observed in nodule meristem descendants. the infection-related expre ... | 2005 | 16258018 |
| ascending migration of endophytic rhizobia, from roots to leaves, inside rice plants and assessment of benefits to rice growth physiology. | rhizobia, the root-nodule endosymbionts of leguminous plants, also form natural endophytic associations with roots of important cereal plants. despite its widespread occurrence, much remains unknown about colonization of cereals by rhizobia. we examined the infection, dissemination, and colonization of healthy rice plant tissues by four species of gfp-tagged rhizobia and their influence on the growth physiology of rice. the results indicated a dynamic infection process beginning with surface col ... | 2005 | 16269768 |
| symbiotic hydrogenase activity in bradyrhizobium sp. (vigna) increases nitrogen content in vigna unguiculata plants. | bradyrhizobium sp. (lupinus) and bradyrhizobium sp. (vigna) mutants in which hydrogenase (hup) activity was affected were constructed and analyzed. vigna unguiculata plants inoculated with the bradyrhizobium sp. (vigna) hup mutant showed reduced nitrogenase activity and also a significant decrease in nitrogen content, suggesting a relevant contribution of hydrogenase activity to plant yield. | 2005 | 16269797 |
| identification and active expression of the mycobacterium tuberculosis gene encoding 5-phospho-{alpha}-d-ribose-1-diphosphate: decaprenyl-phosphate 5-phosphoribosyltransferase, the first enzyme committed to decaprenylphosphoryl-d-arabinose synthesis. | decaprenylphosphoryl-d-arabinose, the lipid donor of mycobacterial d-arabinofuranosyl residues, is synthesized from phosphoribose diphosphate rather than from a sugar nucleotide. the first committed step in the process is the transfer of a 5-phosphoribosyl residue from phosphoribose diphosphate to decaprenyl phosphate to form decaprenylphosphoryl-5-phosphoribose via a 5-phospho-alpha-d-ribose-1-diphosphate:decaprenyl-phosphate 5-phospho-ribosyltransferase. a candidate for the gene encoding this ... | 2005 | 15878857 |
| l-cysteate sulpho-lyase, a widespread pyridoxal 5'-phosphate-coupled desulphonative enzyme purified from silicibacter pomeroyi dss-3(t). | quantitative utilization of l-cysteate (2-amino-3-sulphopropionate) as the sole source of carbon and energy for growth of the aerobic, marine bacterium silicibacter pomeroyi dss-3(t) was observed. the sulphonate moiety was recovered in the medium largely as sulphite, and the appropriate amount of the ammonium ion was also observed. genes [suyab (3-sulpholactate sulpho-lyase)] encoding the known desulphonation reaction in cysteate degradation were absent from the genome, but a homologue of a puta ... | 2006 | 16302849 |
| responses of azorhizobium caulinodans to cadmium stress. | the symbiosis of azorhizobium caulinodans and an annul legume sesbania rostrata was recently found to be tolerant to cadmium pollution by an unknown mechanism. in this study, a. caulinodans ors571 and zy-20 showed much stronger tolerance to cadmium than a mutant ors571-x15 and a common rhizobium sp., with minimum inhibitory concentration values as high as 4 and 5 mm (versus 1 and 0.1 mm) on yeast extract mannitol agar medium, respectively. although cd uptake by all three strains of a. caulinodan ... | 2005 | 16332342 |
| microarray-based detection and typing of the rhizobium nodulation gene nodc: potential of dna arrays to diagnose biological functions of interest. | environmental screening of bacteria for the presence of genes of interest is a challenging problem, due to the high variability of the nucleotide sequence of a given gene between species. here, we tackle this general issue using a particularly well-suited model system that consists of the nodulation gene nodc, which is shared by phylogenetically distant rhizobia. 41mer and 50mer oligonucleotides featuring the nucleotide diversity of two highly conserved regions of the nodc protein were spotted o ... | 2005 | 16332784 |
| survival of azorhizobium caulinodans in the soil and rhizosphere of wetland rice under sesbania rostrata-rice rotation. | the survival of indigenous and introduced strains of azorhizobium caulinodans in flooded soil and in the rice rhizosphere, where in situ sesbania rostrata was incorporated before the rice crop, is reported. the azorhizobia studied were both root and stem nodulating. in a pot experiment, two crop cycles each of inoculated and noninoculated sesbania-rice were compared with two crop cycles of flooded fallow-rice. in a field experiment, the effect of repeated incorporation of in situ s. rostrata in ... | 1989 | 16347853 |
| epiphytic occurrence of azorhizobium caulinodans and other rhizobia on host and nonhost legumes. | a large population of azorhizobium caulinodans was present on sesbania rostrata; up to 5 x 10 cm were found on leaves and fewer were found on flowers. although a. caulinodans was also present on the leaves of sesbania aculeata (nonhost), the populations were much smaller than that observed on s. rostrata. the population of s. aculeata rhizobia on host leaves was less than 30 cm, and their presence on host flowers was sporadic. aeschynomene afraspera and aeschynomene aspera rhizobia, which are pr ... | 1989 | 16348019 |
| epiphytic occurrence of azorhizobium caulinodans and other rhizobia on host and nonhost legumes. | [this corrects the article on p. 2407 in vol. 55.]. | 1989 | 16348065 |
| oxygen uptake and hydrogen-stimulated nitrogenase activity from azorhizobium caulinodans ors571 grown in a succinate-limited chemostat. | succinate-limited continuous cultures of an azorhizobium caulinodans strain were grown on ammonia or nitrogen gas as a nitrogen source. ammonia-grown cells became oxygen limited at 1.7 mum dissolved oxygen, whereas nitrogen-fixing cells remained succinate limited even at dissolved oxygen concentrations as low as 0.9 mum. nitrogen-fixing cells tolerated dissolved oxygen concentrations as high as 41 mum. succinate-dependent oxygen uptake rates of cells from the different steady states ranged from ... | 1991 | 16348585 |
| nitrogen fixation and hydrogen metabolism in relation to the dissolved oxygen tension in chemostat cultures of the wild type and a hydrogenase-negative mutant of azorhizobium caulinodans. | both the wild type and an isogenic hydrogenase-negative mutant of azorhizobium caulinodans growing ex planta on n(2) as the n source were studied in succinate-limited steady-state chemostat cultures under 0.2 to 3.0% dissolved o(2) tension. production or consumption of o(2), h(2), and co(2) was measured with an on-line-connected mass spectrometer. in the range of 0.2 to 3.0%, growth of both the wild type and the mutant was equally dependent on the dissolved o(2) tension: the growth yield decreas ... | 1994 | 16349280 |
| chemo-enzymatic synthesis of allyl penta-n-acetyl-chitopentaose. | cell density cultivation of recombinant escherichia coli strains harboring the nodc gene (encoding chitooligosaccharide synthase) from azorhizobium caulinodans has been previously described as a practical method for the preparation of gram-scale quantities of penta-n-acetyl-chitopentaose. we have now extended this method to the production of allylated derivative of penta-n-acetyl-chitopentaose by using allyl 2-acetamido-2-deoxy-beta-d-glucopyranoside (2) as the initial acceptor for the synthesis ... | 2006 | 16403625 |
| molecular phylogeny based on the 16s rrna gene of elite rhizobial strains used in brazilian commercial inoculants. | nitrogen is often a limiting nutrient, therefore the sustainability of food crops, forages and green manure legumes is mainly associated with their ability to establish symbiotic associations with stem and root-nodulating n2-fixing rhizobia. the selection, identification and maintenance of elite strains for each host are critical. decades of research in brazil resulted in a list of strains officially recommended for several legumes, but their genetic diversity is poorly known. this study aimed a ... | 2006 | 16442259 |
| hfq variant with altered rna binding functions. | the interaction between hfq and rna is central to multiple regulatory processes. using site-directed mutagenesis, we have found a missense mutation in hfq (v43r) which strongly affects2 the rna binding capacity of the hfq protein and its ability to stimulate poly(a) tail elongation by poly(a)-polymerase in vitro. in vivo, overexpression of this hfq variant fails to stimulate rpos-lacz expression and does not restore a normal growth rate in hfq null mutant. cells in which the wild-type gene has b ... | 2006 | 16449205 |
| catabolism of 1,5-anhydro-d-fructose in sinorhizobium morelense s-30.7.5: discovery, characterization, and overexpression of a new 1,5-anhydro-d-fructose reductase and its application in sugar analysis and rare sugar synthesis. | the bacterium sinorhizobium morelense s-30.7.5 was isolated by a microbial screening using the sugar 1,5-anhydro-d-fructose (af) as the sole carbon source. this strain metabolized af by a novel pathway involving its reduction to 1,5-anhydro-d-mannitol (am) and the further conversion of am to d-mannose by c-1 oxygenation. growth studies showed that the af metabolizing capability is not confined to s. morelense s-30.7.5 but is a more common feature among the rhizobiaceae. the af reducing enzyme wa ... | 2006 | 16461673 |
| rhizobial exopolysaccharides: genetic control and symbiotic functions. | specific complex interactions between soil bacteria belonging to rhizobium, sinorhizobium, mesorhizobium, phylorhizobium, bradyrhizobium and azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosacchari ... | 2006 | 16483356 |
| yeast two-hybrid studies on interaction of proteins involved in regulation of nitrogen fixation in the phototrophic bacterium rhodobacter capsulatus. | rhodobacter capsulatus contains two pii-like proteins, glnb and glnk, which play central roles in controlling the synthesis and activity of nitrogenase in response to ammonium availability. here we used the yeast two-hybrid system to probe interactions between these pii-like proteins and proteins known to be involved in regulating nitrogen fixation. analysis of defined protein pairs demonstrated the following interactions: glnb-ntrb, glnb-nifa1, glnb-nifa2, glnb-drat, glnk-nifa1, glnk-nifa2, and ... | 2003 | 12923097 |
| the sesbania root symbionts sinorhizobium saheli and s. teranga bv. sesbaniae can form stem nodules on sesbania rostrata, although they are less adapted to stem nodulation than azorhizobium caulinodans. | sesbania species can establish symbiotic interactions with rhizobia from two taxonomically distant genera, including the sesbania rostrata stem-nodulating azorhizobium sp. and azorhizobium caulinodans and the newly described sinorhizobium saheli and sinorhizobium teranga bv. sesbaniae, isolated from the roots of various sesbania species. a collection of strains from both groups were analyzed for their symbiotic properties with different sesbania species. s. saheli and s. teranga bv. sesbaniae st ... | 1997 | 16535538 |
| azorhizobium doebereinerae sp. nov. microsymbiont of sesbania virgata (caz.) pers. | thirty-four rhizobium strains were isolated from root nodules of the fast-growing woody native species sesbania virgata in different regions of southeast brazil (minas gerais and rio de janeiro states). these isolates had cultural characteristics on yma quite similar to azorhizobium caulinodans (alkalinization, scant extracellular polysaccharide production, fast or intermediate growth rate). they exhibited a high similarity of phenotypic and genotypic characteristics among themselves and to a le ... | 2006 | 16564956 |
| flavonoid-inducible modifications to rhamnan o antigens are necessary for rhizobium sp. strain ngr234-legume symbioses. | rhizobium sp. strain ngr234 produces a flavonoid-inducible rhamnose-rich lipopolysaccharide (lps) that is important for the nodulation of legumes. many of the genes encoding the rhamnan part of the molecule lie between 87 degrees and 110 degrees of pngr234a, the symbiotic plasmid of ngr234. computational methods suggest that 5 of the 12 open reading frames (orfs) within this arc are involved in synthesis (and subsequent polymerization) of l-rhamnose. two others probably play roles in the transpo ... | 2006 | 16672619 |
| fixj: a major regulator of the oxygen limitation response and late symbiotic functions of sinorhizobium meliloti. | sinorhizobium meliloti exists either in a free-living state in the soil or in symbiosis within legume nodules, where the bacteria differentiate into nitrogen-fixing bacteroids. expression of genes involved in nitrogen fixation and associated respiration is governed by two intermediate regulators, nifa and fixk, respectively, which are controlled by a two-component regulatory system fixlj in response to low-oxygen conditions. in order to identify the fixlj regulon, gene expression profiles were d ... | 2006 | 16788198 |
| autoregulation of the misr/miss two-component signal transduction system in neisseria meningitidis. | two-component regulatory systems are involved in processes important for bacterial pathogenesis. the proposed misr/miss (or phop/phoq) system is one of four two-component systems of the obligate human pathogen neisseria meningitidis. inactivation of this system results in loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. misr and the cytoplasmic domain of miss were purified as his6 and maltose binding protein fusion ... | 2006 | 16816178 |
| diverse flavonoids stimulate nodd1 binding to nod gene promoters in sinorhizobium meliloti. | nodd1 is a member of the nodd family of lysr-type transcriptional regulators that mediates the expression of nodulation (nod) genes in the soil bacterium sinorhizobium meliloti. each species of rhizobia establishes a symbiosis with a limited set of leguminous plants. this host specificity results in part from a nodd-dependent upregulation of nod genes in response to a cocktail of flavonoids in the host plant's root exudates. to demonstrate that nodd is a key determinant of host specificity, we e ... | 2006 | 16855231 |
| molecular and functional analysis of nicotinate catabolism in eubacterium barkeri. | the anaerobic soil bacterium eubacterium barkeri catabolizes nicotinate to pyruvate and propionate via a unique fermentation. a full molecular characterization of nicotinate fermentation in this organism was accomplished by the following results: (i) a 23.2-kb dna segment with a gene cluster encoding all nine enzymes was cloned and sequenced, (ii) two chiral intermediates were discovered, and (iii) three enzymes were found, completing the hitherto unknown part of the pathway. nicotinate dehydrog ... | 2006 | 16894175 |
| biochemical activities of three pairs of ehrlichia chaffeensis two-component regulatory system proteins involved in inhibition of lysosomal fusion. | ehrlichia chaffeensis, the etiologic agent of human monocytic ehrlichiosis, replicates in early endosomes by avoiding lysosomal fusion in monocytes and macrophages. in e. chaffeensis we predicted three pairs of putative two-component regulatory systems (tcss) designated plec-pled, ntry-ntrx, and ccka-ctra based on amino acid sequence homology. in the present study to determine biochemical pairs and specificities of the tcss, the recombinant proteins of the three putative histidine kinase (hk) ki ... | 2006 | 16926392 |
| the rna chaperone hfq is essential for the virulence of salmonella typhimurium. | the rna chaperone, hfq, plays a diverse role in bacterial physiology beyond its original role as a host factor required for replication of qbeta rna bacteriophage. in this study, we show that hfq is involved in the expression and secretion of virulence factors in the facultative intracellular pathogen, salmonella typhimurium. a salmonella hfq deletion strain is highly attenuated in mice after both oral and intraperitoneal infection, and shows a severe defect in invasion of epithelial cells and a ... | 2007 | 17163975 |
| identification of novel sinorhizobium meliloti mutants compromised for oxidative stress protection and symbiosis. | employing a novel two-part screen, we identified sinorhizobium meliloti mutants that were both sensitive to hydrogen peroxide and symbiotically defective on the host plant medicago sativa. the mutations affect a wide variety of cellular processes and represent both novel and previously identified genes important in symbiosis. | 2007 | 17172326 |
| identification of novel sinorhizobium meliloti mutants compromised for oxidative stress protection and symbiosis. | employing a novel two-part screen, we identified sinorhizobium meliloti mutants that were both sensitive to hydrogen peroxide and symbiotically defective on the host plant medicago sativa. the mutations affect a wide variety of cellular processes and represent both novel and previously identified genes important in symbiosis. | 2007 | 17172326 |
| the mtmmpl1 early nodulin is a novel member of the matrix metalloendoproteinase family with a role in medicago truncatula infection by sinorhizobium meliloti. | we show here that mtmmpl1, a medicago truncatula nodulin gene previously identified by transcriptomics, represents a novel and specific marker for root and nodule infection by sinorhizobium meliloti. this was established by determining the spatial pattern of mtmmpl1 expression and evaluating gene activation in the context of various plant and bacterial symbiotic mutant interactions. the mtmmpl1 protein is the first nodulin shown to belong to the large matrix metalloendoproteinase (mmp) family. w ... | 2007 | 17293436 |
| nod factor perception during infection thread growth fine-tunes nodulation. | bacterial nodulation factors (nfs) are essential signaling molecules for the initiation of a nitrogen-fixing symbiosis in legumes. nfs are perceived by the plant and trigger both local and distant responses, such as curling of root hairs and cortical cell divisions. in addition to their requirement at the start, nfs are produced by bacteria that reside within infection threads. to analyze the role of nfs at later infection stages, several phases of nodulation were studied by detailed light and e ... | 2007 | 17313164 |
| a symbiotic plant peroxidase involved in bacterial invasion of the tropical legume sesbania rostrata. | aquatic nodulation on the tropical legume sesbania rostrata occurs at lateral root bases via intercellular crack-entry invasion. a gene was identified (srprx1) that is transiently up-regulated during the nodulation process and codes for a functional class iii plant peroxidase. the expression strictly depended on bacterial nodulation factors (nfs) and could be modulated by hydrogen peroxide, a downstream signal for crack-entry invasion. expression was not induced after wounding or pathogen attack ... | 2007 | 17384158 |
| amoeba-resisting bacteria and ventilator-associated pneumonia. | to evaluate the role of amoeba-associated bacteria as agents of ventilator-associated pneumonia (vap), we tested the water from an intensive care unit (icu) every week for 6 months for such bacteria isolates; serum samples and bronchoalveolar lavage samples (bal) were also obtained from 30 icu patients. bal samples were examined for amoeba-associated bacteria dna by suicide-polymerase chain reaction, and serum samples were tested against icu amoeba-associated bacteria. a total of 310 amoeba-asso ... | 2003 | 12890321 |
| production and chitinase-binding ability of lipo-chitopentaose nodulation factor. | the penta-n-acetyl-chitopentaose 2 has been prepared by using recombinant e. coli strains harboring the nodc gene (encoding chitooligosaccharide synthase) from azorhizobium caulinodans. then, the deacetylase nodb removed the n-acetyl moiety from the nonreducing terminus of 2 to give tetra-n-acetyl-chitopentaose 3. n-acylation of 3 with stearyl chloride was performed in dmf containing water and provided the corresponding lipo-chitopentaose nodulation factor 4. a binding chitinase assay indicated ... | 2007 | 17518353 |
| microarray for serotyping of bartonella species. | bacteria of the genus bartonella are responsible for a large variety of human and animal diseases. serological typing of bartonella is a method that can be used for differentiation and identification of bartonella subspecies. | 2007 | 17593301 |
| comparative transcriptome analysis reveals common and specific tags for root hair and crack-entry invasion in sesbania rostrata. | the tropical legume sesbania rostrata provides its microsymbiont azorhizobium caulinodans with versatile invasion strategies to allow nodule formation in temporarily flooded habitats. in aerated soils, the bacteria enter via the root hair curling mechanism. submergence prevents this epidermal invasion by accumulation of inhibiting concentrations of ethylene and, under these conditions, the bacterial colonization occurs via intercellular cortical infection at lateral root bases. the transcriptome ... | 2007 | 17600136 |
| evidence for functional differentiation of duplicated nifh genes in azorhizobium caulinodans. | azorhizobium caulinodans is a symbiotic diazotroph that contains duplicated nifh genes. this study focused on the biological sense behind the duplication. in-frame deletion mutants of nifh1 and nifh2 were constructed in order to analyze nitrogen fixation activity, both in symbiosis and in free-living conditions. symbiotic nitrogen fixation activity was not affected by deletion of nifh1 or nifh2, while free-living nitrogen fixation activity was significantly decreased. deletion of nifh1 had a sig ... | 2007 | 17651409 |
| rhizobial factors required for stem nodule maturation and maintenance in sesbania rostrata-azorhizobium caulinodans ors571 symbiosis. | the molecular and physiological mechanisms behind the maturation and maintenance of n(2)-fixing nodules during development of symbiosis between rhizobia and legumes still remain unclear, although the early events of symbiosis are relatively well understood. azorhizobium caulinodans ors571 is a microsymbiont of the tropical legume sesbania rostrata, forming n(2)-fixing nodules not only on the roots but also on the stems. in this study, 10,080 transposon-inserted mutants of a. caulinodans ors571 w ... | 2007 | 17720818 |
| production of l-carnitine by secondary metabolism of bacteria. | abstract: the increasing commercial demand for l-carnitine has led to a multiplication of efforts to improve its production with bacteria. the use of different cell environments, such as growing, resting, permeabilized, dried, osmotically stressed, freely suspended and immobilized cells, to maintain enzymes sufficiently active for l-carnitine production is discussed in the text. the different cell states of enterobacteria, such as escherichia coli and proteus sp., which can be used to produce l- ... | 2007 | 17910757 |
| phage specificity and lipopolysaccarides of stem- and root-nodulating bacteria (azorhizobium caulinodans, sinorhizobium spp., and rhizobium spp.) of sesbania spp. | phage susceptibility pattern and its correlation with lipopolysaccharide (lps) and plasmid profiles may help in understanding the phenotypic and genotypic diversity among highly promiscuous group of rhizobia nodulating sesbania spp.; 43 phages were from two stem-nodulating bacteria of s. rostrata and 16 phages were from root-nodulating bacteria of s. sesban, s. aegyptica and s. rostrata. phage susceptibility pattern of 38 sesbania nodulating bacteria was correlated with their lps rather than pla ... | 2008 | 17989956 |
| misr/miss two-component regulon in neisseria meningitidis. | two-component regulatory systems are involved in processes important for bacterial pathogenesis. inactivation of the misr/miss system in neisseria meningitidis results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. one hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the misr/miss (misr/s) system were identified by transcriptional profiling of the nmbmisr mutant and ... | 2008 | 18056476 |
| misr/miss two-component regulon in neisseria meningitidis. | two-component regulatory systems are involved in processes important for bacterial pathogenesis. inactivation of the misr/miss system in neisseria meningitidis results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. one hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the misr/miss (misr/s) system were identified by transcriptional profiling of the nmbmisr mutant and ... | 2008 | 18056476 |
| social bacteria and asocial eukaryotes. | | 2008 | 18199122 |
| functional nodfe genes are present in sinorhizobium sp. strain mus10, a symbiont of the tropical legume sesbania rostrata. | we have cloned the nodfe operon from sinorhizobium sp. strain mus10. mus10 nodf shows sequence homology to acyl carrier protein and enables an s. meliloti nodf mutant to effectively nodulate alfalfa. our results demonstrate the occurrence of nodfe in a symbiont that nodulates a legume host not belonging to the galegoid group. | 2008 | 18326678 |
| diversity of bacterial communities in container habitats of mosquitoes. | we investigated the bacterial diversity of microbial communities in water-filled, human-made and natural container habitats of the mosquitoes aedes aegypti and aedes albopictus in suburban landscapes of new orleans, louisiana in 2003. we collected water samples from three classes of containers, including tires (n = 12), cemetery urns (n = 23), and miscellaneous containers that included two tree holes (n = 19). total genomic dna was extracted from water samples, and 16s ribosomal dna fragments (o ... | 2008 | 18373113 |
| induction of endophytic colonization in rice (oryza sativa l.) tissue culture plants by azorhizobium caulinodans. | endophytic colonization in rice was induced using rhizobia. dehusked seeds of rice hybrid, corh2, were used as explants for induction of calli. ms medium was modified with 2,4-d (2.5 mg l(-1)) and kinetin (0.2 mg l(-1)) for callus induction. well-developed calli were inoculated with azorhizobium caulinodans strains ors 571 and aa-sk-5 by means of imbibition. all treated calli had significant increases in protein content, total nitrogen and nitrogenase activity. imbibition of ors 571 had signific ... | 2008 | 18379880 |
| genome sequence of the beta-rhizobium cupriavidus taiwanensis and comparative genomics of rhizobia. | we report the first complete genome sequence of a beta-proteobacterial nitrogen-fixing symbiont of legumes, cupriavidus taiwanensis lmg19424. the genome consists of two chromosomes of size 3.42 mb and 2.50 mb, and a large symbiotic plasmid of 0.56 mb. the c. taiwanensis genome displays an unexpected high similarity with the genome of the saprophytic bacterium c. eutrophus h16, despite being 0.94 mb smaller. both organisms harbor two chromosomes with large regions of synteny interspersed by speci ... | 2008 | 18490699 |
| in silico identification of genes involved in selenium metabolism: evidence for a third selenium utilization trait. | selenium (se) is a trace element that occurs in proteins in the form of selenocysteine (sec) and in trnas in the form of selenouridine (seu). selenophosphate synthetase (seld) is required for both utilization traits. however, previous research also revealed selds in two organisms lacking sec and seu, suggesting a possible additional use of se that is dependent on seld. | 2008 | 18510720 |
| the genome of the versatile nitrogen fixer azorhizobium caulinodans ors571. | biological nitrogen fixation is a prokaryotic process that plays an essential role in the global nitrogen cycle. azorhizobium caulinodans ors571 has the dual capacity to fix nitrogen both as free-living organism and in a symbiotic interaction with sesbania rostrata. the host is a fast-growing, submergence-tolerant tropical legume on which a. caulinodans can efficiently induce nodule formation on the root system and on adventitious rootlets located on the stem. | 2008 | 18522759 |
| an outer membrane autotransporter, aoaa, of azorhizobium caulinodans is required for sustaining high n2-fixing activity of stem nodules. | in this study, we investigated the function of a putative high-molecular-weight outer membrane protein, azorhizobial outer membrane autotransporter a (aoaa), of azorhizobium caulinodans ors571. sequence analysis revealed that aoaa was an autotransporter protein belonging to the type v protein secretion system. azorhizobium caulinodans forms n(2)-fixing nodules on the stems and roots of sesbania rostrata. the sizes of stem nodules formed by an aoaa mutant having transposon insertion within this o ... | 2008 | 18557786 |
| decaprenylphosphoryl arabinofuranose, the donor of the d-arabinofuranosyl residues of mycobacterial arabinan, is formed via a two-step epimerization of decaprenylphosphoryl ribose. | the major cell wall polysaccharide of mycobacteria is a branched-chain arabinogalactan in which arabinan chains are attached to the 5 carbon of some of the 6-linked galactofuranose residues; these arabinan chains are composed exclusively of d-arabinofuranose (araf) residues. the immediate precursor of the polymerized araf is decaprenylphosphoryl-d-araf, which is derived from 5-phosphoribose 1-diphosphate (prpp) in an undefined manner. on the basis of time course, feedback, and chemical reduction ... | 2005 | 16291675 |
| ameba-associated microorganisms and diagnosis of nosocomial pneumonia. | to elucidate the role of ameba-associated microorganisms (aams) as etiologic agents of pneumonia, we screened for legionella spp., parachlamydia acanthamoeba, afipia sp., bosea spp., bradyrhizobium spp., mesorhizobium amorphae, rasbo bacterium, azorhizobium caulinodans, acanthamoeba polyphaga mimivirus, and conventional microorganisms in 210 pneumonia patients in intensive-care units by using culture, polymerase chain reaction, and serologic testing. these resulted in 59 diagnoses in 40 patients ... | 2006 | 16494750 |
| comprehensive assessment of the regulons controlled by the fixlj-fixk2-fixk1 cascade in bradyrhizobium japonicum. | symbiotic n(2) fixation in bradyrhizobium japonicum is controlled by a complex transcription factor network. part of it is a hierarchically arranged cascade in which the two-component regulatory system fixlj, in response to a moderate decrease in oxygen concentration, activates the fixk(2) gene. the fixk(2) protein then activates not only a number of genes essential for microoxic respiration in symbiosis (fixnoqp and fixghis) but also further regulatory genes (rpon(1), nnrr, and fixk(1)). the re ... | 2008 | 18689489 |
| prediction of sinorhizobium meliloti srna genes and experimental detection in strain 2011. | small non-coding rnas (srnas) have emerged as ubiquitous regulatory elements in bacteria and other life domains. however, few srnas have been identified outside several well-studied species of gamma-proteobacteria and thus relatively little is known about the role of rna-mediated regulation in most other bacterial genera. here we have conducted a computational prediction of putative srna genes in intergenic regions (igrs) of the symbiotic alpha-proteobacterium s. meliloti 1021 and experimentally ... | 2008 | 18793445 |
| molecular determinants of a symbiotic chronic infection. | rhizobial bacteria colonize legume roots for the purpose of biological nitrogen fixation. a complex series of events, coordinated by host and bacterial signal molecules, underlie the development of this symbiotic interaction. rhizobia elicit de novo formation of a novel root organ within which they establish a chronic intracellular infection. legumes permit rhizobia to invade these root tissues while exerting control over the infection process. once rhizobia gain intracellular access to their ho ... | 2008 | 18983260 |
| the blcc (attm) lactonase of agrobacterium tumefaciens does not quench the quorum-sensing system that regulates ti plasmid conjugative transfer. | the conjugative transfer of agrobacterium plasmids is controlled by a quorum-sensing system consisting of trar and its acyl-homoserine lactone (hsl) ligand. the acyl-hsl is essential for the trar-mediated activation of the ti plasmid tra genes. strains a6 and c58 of agrobacterium tumefaciens produce a lactonase, blcc (attm), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. we tested this hypothesis by examining the effects of the mutatio ... | 2009 | 19011037 |
| the blcc (attm) lactonase of agrobacterium tumefaciens does not quench the quorum-sensing system that regulates ti plasmid conjugative transfer. | the conjugative transfer of agrobacterium plasmids is controlled by a quorum-sensing system consisting of trar and its acyl-homoserine lactone (hsl) ligand. the acyl-hsl is essential for the trar-mediated activation of the ti plasmid tra genes. strains a6 and c58 of agrobacterium tumefaciens produce a lactonase, blcc (attm), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. we tested this hypothesis by examining the effects of the mutatio ... | 2009 | 19011037 |
| comparative genomic analysis of carbon and nitrogen assimilation mechanisms in three indigenous bioleaching bacteria: predictions and validations. | carbon and nitrogen fixation are essential pathways for autotrophic bacteria living in extreme environments. these bacteria can use carbon dioxide directly from the air as their sole carbon source and can use different sources of nitrogen such as ammonia, nitrate, nitrite, or even nitrogen from the air. to have a better understanding of how these processes occur and to determine how we can make them more efficient, a comparative genomic analysis of three bioleaching bacteria isolated from mine s ... | 2008 | 19055775 |
| comparative genomic analyses of nickel, cobalt and vitamin b12 utilization. | nickel (ni) and cobalt (co) are trace elements required for a variety of biological processes. ni is directly coordinated by proteins, whereas co is mainly used as a component of vitamin b12. although a number of ni and co-dependent enzymes have been characterized, systematic evolutionary analyses of utilization of these metals are limited. | 2009 | 19208259 |
| genome sequences of three agrobacterium biovars help elucidate the evolution of multichromosome genomes in bacteria. | the family rhizobiaceae contains plant-associated bacteria with critical roles in ecology and agriculture. within this family, many rhizobium and sinorhizobium strains are nitrogen-fixing plant mutualists, while many strains designated as agrobacterium are plant pathogens. these contrasting lifestyles are primarily dependent on the transmissible plasmids each strain harbors. members of the rhizobiaceae also have diverse genome architectures that include single chromosomes, multiple chromosomes, ... | 2009 | 19251847 |
| a novel endo-hydrogenase activity recycles hydrogen produced by nitrogen fixation. | nitrogen (n(2)) fixation also yields hydrogen (h(2)) at 1:1 stoichiometric amounts. in aerobic diazotrophic (able to grow on n(2) as sole n-source) bacteria, orthodox respiratory hupsl-encoded hydrogenase activity, associated with the cell membrane but facing the periplasm (exo-hydrogenase), has nevertheless been presumed responsible for recycling such endogenous hydrogen. | 2009 | 19277114 |
| rhizobium sp. strain ngr234 possesses a remarkable number of secretion systems. | rhizobium sp. strain ngr234 is a unique alphaproteobacterium (order rhizobiales) that forms nitrogen-fixing nodules with more legumes than any other microsymbiont. we report here that the 3.93-mbp chromosome (cngr234) encodes most functions required for cellular growth. few essential functions are encoded on the 2.43-mbp megaplasmid (pngr234b), and none are present on the second 0.54-mbp symbiotic plasmid (pngr234a). among many striking features, the 6.9-mbp genome encodes more different secreti ... | 2009 | 19376903 |
| the rho gtpase inactivation domain in vibrio cholerae martx toxin has a circularly permuted papain-like thiol protease fold. | a rho gtpase inactivation domain (rid) has been discovered in the multifunctional, autoprocessing rtx toxin rtxa from vibrio cholerae. the rid domain causes actin depolymerization and rounding of host cells through inactivation of the small rho gtpases rho, rac, and cdc42. with only a few toxin proteins containing rid domains in the current sequence database, the structure and molecular mechanisms of this domain are unknown. using comparative sequence and structural analyses, we report homology ... | 2009 | 19434753 |
| calcium spiking patterns and the role of the calcium/calmodulin-dependent kinase ccamk in lateral root base nodulation of sesbania rostrata. | nodulation factor (nf) signal transduction in the legume-rhizobium symbiosis involves calcium oscillations that are instrumental in eliciting nodulation. to date, ca2+ spiking has been studied exclusively in the intracellular bacterial invasion of growing root hairs in zone i. this mechanism is not the only one by which rhizobia gain entry into their hosts; the tropical legume sesbania rostrata can be invaded intercellularly by rhizobia at cracks caused by lateral root emergence, and this proces ... | 2009 | 19470588 |
| comparative genome-wide transcriptional profiling of azorhizobium caulinodans ors571 grown under free-living and symbiotic conditions. | the whole-genome sequence of the endosymbiotic bacterium azorhizobium caulinodans ors571, which forms nitrogen-fixing nodules on the stems and roots of sesbania rostrata, was recently determined. the sizes of the genome and symbiosis island are 5.4 mb and 86.7 kb, respectively, and these sizes are the smallest among the sequenced rhizobia. in the present study, a whole-genome microarray of a. caulinodans was constructed, and transcriptomic analyses were performed on free-living cells grown in ri ... | 2009 | 19542345 |
| nitrogen fixation in eukaryotes--new models for symbiosis. | nitrogen, a component of many bio-molecules, is essential for growth and development of all organisms. most nitrogen exists in the atmosphere, and utilisation of this source is important as a means of avoiding nitrogen starvation. however, the ability to fix atmospheric nitrogen via the nitrogenase enzyme complex is restricted to some bacteria. eukaryotic organisms are only able to obtain fixed nitrogen through their symbiotic interactions with nitrogen-fixing prokaryotes. these symbioses involv ... | 2007 | 17408485 |
| metabolic analysis of the soil microbe dechloromonas aromatica str. rcb: indications of a surprisingly complex life-style and cryptic anaerobic pathways for aromatic degradation. | initial interest in dechloromonas aromatica strain rcb arose from its ability to anaerobically degrade benzene. it is also able to reduce perchlorate and oxidize chlorobenzoate, toluene, and xylene, creating interest in using this organism for bioremediation. little physiological data has been published for this microbe. it is considered to be a free-living organism. | 2009 | 19650930 |
| chemoenzymatic synthesis of gdp-l-fucose and the lewis x glycan derivatives. | lewis x (le(x))-containing glycans play important roles in numerous cellular processes. however, the absence of robust, facile, and cost-effective methods for the synthesis of le(x) and its structurally related analogs has severely hampered the elucidation of the specific functions of these glycan epitopes. here we demonstrate that chemically defined guanidine 5'-diphosphate-beta-l-fucose (gdp-fucose), the universal fucosyl donor, the le(x) trisaccharide, and their c-5 substituted derivatives ca ... | 2009 | 19805264 |
| legionella pneumophila secretes an endoglucanase that belongs to the family-5 of glycosyl hydrolases and is dependent upon type ii secretion. | examination of cell-free culture supernatants revealed that legionella pneumophila strains secrete an endoglucanase activity. legionella pneumophila lspf mutants were deficient for this activity, indicating that the endoglucanase is secreted by the bacterium's type ii protein secretion (t2s) system. inactivation of cela, encoding a member of the family-5 of glycosyl hydrolases, abolished the endoglucanase activity in l. pneumophila culture supernatants. the cloned cela gene conferred activity up ... | 2009 | 19817866 |
| transcriptome profiling defines a novel regulon modulated by the lysr-type transcriptional regulator mext in pseudomonas aeruginosa. | the lysr-family regulator mext modulates the expression of the mexef-oprn efflux system in the human pathogen pseudomonas aeruginosa. recently, we demonstrated that mext regulates certain virulence phenotypes, including the type-three secretion system and early attachment independent of its role in regulating mexef-oprn. in this study, transcriptome profiling was utilized to investigate the global nature of mext regulation in p. aeruginosa pao1 and an isogenic mexef mutant. twelve genes of unkno ... | 2009 | 19846594 |
| partial redundancy in the synthesis of the d-arabinose incorporated in the cell wall arabinan of corynebacterineae. | the major cell wall carbohydrate of corynebacterineae is arabinogalactan (ag), a branched polysaccharide that is essential for the physiology of these bacteria. decaprenylphosphoryl-d-arabinose (dpa), the lipid donor of d-arabinofuranosyl residues of ag, is synthesized through a series of unique biosynthetic steps, the last one being the epimerization of decaprenylphosphoryl-beta-d-ribose (dpr) into dpa, which is believed to proceed via a sequential oxidation-reduction mechanism. two proteins fr ... | 2008 | 18667564 |